As is known, automatic transmissions need an oil pump for delivering pressure and lubricating medium for the supply of hydraulically actuated frictional shift elements and for the lubrication of the transmission's gear teeth and bearings. From EP 1 598 576 A1 an automatic transmission is known, whose transmission input shaft is connected via a hydrodynamic torque converter to a drive motor and whose oil pump is driven by a pump wheel of the torque converter connected to a crankshaft of the drive motor. This oil pump is arranged with its axis parallel to the transmission input shaft and to the torque converter and a chain drive being provided for driving the oil pump. In this case, it is provided that the pump wheel of the torque converter is connected to a crankshaft of the drive motor, a turbine wheel of the torque converter is connected to the transmission input shaft, and the pump wheel has a hub, usually called the “converter neck”, which is mounted radially, via a slide bearing, on a hub fixed onto the transmission housing and usually called the “guide-wheel spindle”. The guide-wheel spindle also is positively connected to a guide-wheel of the torque converter. The chain drive for driving the oil pump has a driven chain wheel which is positively connected, via a driving finger of the converter socket, to the torque converter, a follower chain wheel connected rotationally fixed to a pump drive shaft, and a chain that transmits the rotation of the driven chain wheel is arranged on the side of the torque converter remote from the drive motor in the area of an outer wall of the transmission housing on the converter side, and mounted radially via a slide bearing—such as the converter neck of the torque converter—on the guide-wheel spindle of the transmission fixed on the transmission housing. The axial mounting of the driven chain wheel is ensured by check-rings positioned on both sides of the driven chain wheel.
The purpose of the present invention is to provide a pump drive of an automatic transmission with a hydrodynamic torque converter and an oil pump driven by a pump wheel of the torque converter, whose connection on the torque side to the torque converter is optimized in terms of cost and ease of assembly.